1. Field of the Invention
The present invention relates to a crimp terminal and a structure for connecting the crimp terminal and an electric wire.
2. Description of the Related Art
Reduction in the weight of a vehicle has a great influence on improvement of fuel consumption. Currently, reduction in carbon dioxide emission is required, and especially in an electric vehicle and a hybrid vehicle where the amount of wire harnesses used therein is larger than that in a petrol-driven vehicle, it is preferable that an electric wire made of aluminum and an aluminum alloy of lightweight materials be used for a wire harness. However, in an aluminum-made wire made of aluminum or an aluminum alloy being crimped and connected to a crimp terminal made of copper or a copper alloy, when water exists where the electric wire and the crimp terminal contact each other, this water serves as an electrolyte between dissimilar metals. In dissimilar metals such as a copper-made terminal and an aluminum-made conductor, when an electric circuit is formed through an electrolyte, corrosion of a metal having a baser potential (for example, the aluminum conductor) is accelerated due to difference in corrosion potential of the dissimilar metals. In other words, galvanic corrosion occurs.
A terminal has been proposed that is capable of preventing water from entering the inside of a crimping portion after crimping while achieving assured water stop property and high reliability over the long term (see Japanese Patent Application Laid-open No. 2013-62206, for example). As illustrated in FIGS. 9A and 9B, this female crimp terminal (crimp terminal) 501 is crimped in such a manner that a pair of barrel pieces 505 of a crimping portion 503 enclose an electric wire exposed portion 515 of an aluminum core 513 exposed from a coating tip 511 of an insulating coating 509 of an aluminum wire 507 that is an insulated wire. Thereafter, a step part of an overlap 517 formed by overlapping the barrel pieces 505 and a step part of an overlap 521 on the tip end side formed by crimping the front side ends of the barrel pieces 505 to a crimping bottom 519 of the crimping portion 503 are welded by a laser seam welding machine. In this manner, water is prevented from entering the inside of the crimping portion 503 after crimping.
The conventional female crimp terminal 501 disclosed in Japanese Patent Application Laid-open No. 2013-62206, however, has a cylindrical structure in which the crimping portion 503 is welded, causing no space for bending the aluminum wire 507. The female crimp terminal 501 is thus hard to take on such a structure (protruding shape, for example) as to increase the fixing force by bending the aluminum wire 507. Consequently, the female crimp terminal 501 may not be able to ensure sufficient fixing force for the aluminum wire 507. This problem becomes prominent especially for the case where the aluminum wire 507 of small diameter (0.5 sq or less) is used.